The first goal of this core is to document reports of incident cases of cancer by obtaining the medical records, which also serve to provide detailed information about tumor characteristics including site, stage, grade, and histopathologic patterns. The second goal is to identify all deaths among participants, and to ascertain the cause. The third goal of the core is to obtain tissue samples for cancers of the breast, colorectum, and ovary. Since the inception of the cohort in 1976, we have developed and refined increasingly efficient methods to achieve each of these goals. The trust and mutual respect that has evolved over the past twenty-four years between the investigators and participants has led to an extremely high degree of cooperation in securing permission to review medical records, and from the families in ascertaining the details of the cause of death Medical records are reviewed by physicians according to uniform standardized criteria to confirm the diagnoses and obtain details of the histopathology. We have achieved a high degree of computer assisted automation to maximize efficiency and completeness of follow-up. We also utilize information form state tumor registries. We learn of most deaths through the questionnaire mailings, and search the National Death Index for non-respondents after each 2-year questionnaire cycle. We have developed algorithms to maximally utilize the information from the National Death Index to insure complete follow-up, while minimizing the number of extra death certificates obtained for potential matches. Similarly, we have developed procedures to obtain pathology blocks for breast cancer cases, and now propose to extend this valuable resource to colorectal and ovarian cancer. Despite the exponential increase in cancer cases and deaths in this cohort, we have succeeded in maintaining virtually complete follow-up with only modest increases in personnel, due to the continuing evolution of more efficient procedures. The investigators and stuff supported by this core have considerable experience in achieving these aims, Ms. Egan and Dr. Stampfer share over forty years cumulative experience in these roles. This core serves each of the four projects by providing the accurate and detailed information on outcomes.